bacterial anatomy

Question 1

define amphipathic

Answer 1

hydrophilic and hydrophobic in different areas

Question 2

Define passive diffusion (3)

Answer 2

1. transporter independent
2. the combined concentration of solutes passively tries to reach equilibrium
3. uptake increases in a linear fashion, but will plateau when inside conc. reaches outside

Question 3

define facilitated diffusion

Answer 3

1. independent of membrane permeability
2. example is a porin, which is proteins that make a hole through the membrane, allowing molecules up to a certain size through
3. uptake levels will rise as outer conc rises, but will reach max saturation. uptake will plateau when inner and outer conc. reaches equilibrium

Question 4

the lower the km,

Answer 4

the higher the affinity of the channel, more activity

Question 5

is active transport dependent on a transporter?

Answer 5

yes

Question 6

Define the kinetics of active transport

Answer 6

uptake will plateau at a point. however, concentration inside can go above outside concentration

Question 7

what do uni-, sym, and antiporters have in common?

Answer 7

all are unidirectional, any kind of transport

Question 8

define uniporters

Answer 8

They move one specific substance in one direction

Used for either facilitated diffusion or active transport

Question 9

define symporters

Answer 9

They move two specific molecules in one direction at the same time
Used for either facilitated diffusion or active transport

Question 10

define antiporters

Answer 10

Two specific molecules are transported in opposite directions
Used for either facilitated diffusion or active transport

Question 11

what are two functions of the cell wall?

Answer 11

resist osmotic pressure caused by the entry of water, and define cell shape

Question 12

define periplasm

Answer 12

gap between cell wall and interior plasma membrane

Question 13

What is the difference between peptidoglycan units on gram positive and negative units?

Answer 13

Gram negative have DAP on their string of amino acids, while gram positive uses Lys in the same spot

Question 14

bridges between layers of the peptidoglycan in gram negative

Answer 14

direct peptide bond between the amino acid chains of each layer

Question 15

bridges between layers of the peptidoglycan in gram positive

Answer 15

indirect bonding between layers through a bridge of glycenes

Question 16

how does the cell wall grow? (3 steps)

Answer 16

1. preformed units are brought to the cell wall
2. autolysin comes in and cuts the cell wall, allowing new units to be added to the cell wall
3. bridges are then formed between the layers through transpeptidation

Question 17

how penicillin works

Answer 17

when the cell wall is growing, beta lactams in penicillin prevent new transpeptidation linkages between layers of the peptidoglycan layer.

Question 18

why does penicillin only work on gram + bacteria

Answer 18

Gram - bacteria have the glycocalyx that protects them from penicillin, since it is a large molecule

Question 19

how does lysozyme work?

Answer 19

it cleaves the beta 1-4 linkages between N-glucosamine and acetyl-muramic acid. it works on cell that are growing, and cells that are not. it cuts the linkages between peptidoglycan units

Question 20

What is the significance of Lipid A to the body?

Answer 20

only found on the LPS layer, no body cell have LPS, the body knows there is an intruder

Question 21

what is the LPS impermeable to?

Answer 21

larger proteins, ploysaccharides, and H+